The present invention relates to an apparatus for treating evaporated fuel for an internal combustion engine, and more particularly, to a canister module with integrated components.
Conventionally, an evaporated fuel treatment apparatus in a fuel system of an internal combustion engine is structured, as shown in FIG. 6, such that a fill check valve 20xe2x80x2 and a cut off valve 30xe2x80x2 are secured to a topmost portion of a fuel tank 41 via grommets 42 and 43 and connected to a canister 44 provided in another place by rubber hoses 45 and 46, and a purge pipe 44a of the canister 44 is connected to a suction pipe 51 on an upstream side of a throttle valve 49 via a vacuum control valve (VCV) 48 opened and closed in accordance with a computer control on the basis of an electric signal from an electric control unit (ECU) 47, whereby an evaporated fuel collected at a time when a rotation of an engine increases is sucked due to a negative pressure in the suction pipe 51 and is burned.
In the fill check valve 20xe2x80x2, since a fuel vapor pressure within the fuel tank 41 is increased at a time of supplying a fuel, a diaphragm 2 is lifted up against a diaphragm spring 4, a diaphragm valve 20a is opened, and the evaporated fuel within the fuel tank 41 flows as shown by an arrow and is adsorbed to the canister 44. Since a float valve body 7 is submerged in the fuel when the fuel tank is filled with the fuel, the float valve body 7 floats due to a buoyancy and closes a float valve seat 6, a float valve 7a is closed and a stream of the evaporated fuel is shut off.
Further, the cut off valve 30xe2x80x2 corresponds to an open/close valve for preventing the fuel within the fuel tank 41 from flowing out to an outside via the canister 44 when a vehicle rolls sideways, and is structured such that a cut off valve body 18 is brought into contact with a cut off valve seat 30c due to urging of a cut off valve spring 19 so as to close the cut off valve 30xe2x80x2 when the vehicle rolls sideways. Further, the cut off valve 30xe2x80x2 is provided with a positive pressure safety valve 30b for reducing the pressure within the fuel tank 41 if the cut off valve body 18 should attach to the cut off valve seat 30c. 
On the contrary, a positive and negative pressure check valve 40xe2x80x2 provided within the canister 44 corresponds to an open/close valve for reducing the pressure within the fuel tank 41. This valve is structured such that when an inside of the fuel tank 41 is cooled and the pressure is educed, a negative pressure check valve 40d opens so as to return the pressure and when the pressure within the fuel tank is increased, a diaphragm 40c is lifted up so as to open a diaphragm valve and to reduce the pressure, thereby preventing the fuel tank 41 from being broken.
Accordingly, the rubber hoses 45 and 46 are always filled with the evaporated fuel, and the evaporated fuel is slightly discharged to the atmosphere through a rubber material of the rubber hoses 45 and 46 due to the pressure increase within the fuel tank 41. In particular, since the rubber hose 45 for connecting the fill check valve 20xe2x80x2 to the canister 44 has a large diameter so as to reduce a flow path resistance, a discharge area is great and a discharge amount of the evaporated fuel is large. These discharge amounts are not in problem in the case that an onboard refueling vapor recovery regulation is not so severe, however, when the regulation becomes more severe, even a slight discharge amount is in problem. Further, there is a strong desire that the parts should be integrated for a recent module production and should be made a module corresponding to reduction of the number of parts for reducing cost. Accordingly, an object of the present invention is to provide a canister module which can reduce a discharge amount of the evaporated fuel to the atmosphere and can be manufactured in accordance with a module production.
In order to achieve the object mentioned above, in accordance with a first aspect of the present invention, there is provided a canister module comprising:
at least one open/close valve opening or closing due to a pressure within a fuel tank or a buoyancy from a fuel and opening and closing a passage connecting the fuel tank and an absorbent storage chamber, the open/close valve being assembled in a module main body so as to form a valve module; and
a cover portion for covering a cover side of the open/close valve of the valve module so as to keep an airtight condition of a bonding portion, thereby forming a passage portion for an evaporated fuel by the cover portion and the module main body.
Further, the structure may be made such that at least a fill check valve of the open/close valve is assembled in the module main body so as to form the valve module. Still further, the cover for the open/close valve assembled in the module main body may be integrally formed with the cover portion of the canister case, whereby it is possible to omit the cover for the open/close valve.
In accordance with a second aspect of the present invention, there is provided a canister module comprising:
a diaphragm valve chamber provided in a module main body and communicated with a float valve;
a valve chamber provided within the diaphragm valve chamber and arranged apart from the diaphragm valve chamber;
a positive pressure check valve, a negative pressure check valve, a positive pressure safety valve and a cut off valve, each having one opening portion disposed within the valve chamber;
a diaphragm valve seat provided in a center of the diaphragm chamber and used for opening and closing a passage;
a diaphragm brought into contact with the diaphragm valve seat due to a pressing force of an elastic member;
a diaphragm cover surrounding the diaphragm in such a manner as to keep an airtight condition and having an opening for introducing a pressure in the diaphragm chamber to an outside; and
a communication hole for communicating the valve chamber with the passage,
wherein an outer end portion of the passage is connected to the canister in such a manner as to keep an airtight condition, and the module main body is engaged with a fuel tank in such a manner as to keep an airtight condition.